Treating detergent alkylate

ABSTRACT

METHOD FOR TREATING RAW DETERGENT ALKYLATE IN ORDER TO IMPROVE THE COLOR AND ODOR CHARACTERISTICS OF THE ALKYL BENZENE SULFONTES PRODUCED FROM THE ALKYLATE BY CONTACTING THE RAW ALKYLATE WITH ACTIVATD CHARCOAL AND THEREAFTER SELECTIVELY HYDROGENATING THE CONTACTED ALKYLATE TO AVOID HYDROGENATING THE ALKYL BENZENE COMPOUNDS, SAID HYDROGENATION BEING CARRIED OUT B CONTACTING SAID CONTACTED DETERGENT ALKYLATE WITH A HYDROGEN CONTAINING GAS IN THE PRESENCE OF A CATALYST AT A TEMPERATURE IN THE RANGE OF FROM ABOUT 50*F.TO ABOUT 200*F.AND AT A PRESURE IN THE RANGE OF FROM ABOUT 5 P.S.I.G. TO ABOUT 50 P.S.I.G.

United States Patent 3,646,238 TREATING DETERGENT ALKYLATE Harry E. Jacobs, Glenwood, Ill., assignor to Atlantic Richfield Company, New York, N.Y. N0 Drawing. Filed July 13, 1970, Ser. No. 54,564 Int. Cl. C07c 7/00, 3/50 US. Cl. 260-674 A 10 Claims ABSTRACT OF THE DISCLOSURE Method for treating raw detergent alkylate in order to improve the color and odor characteristics of the alkyl benzene sulfonates produced from the alkylate by contacting the raw alkylate with activated charcoal and thereafter selectively hydrogenating the contacted alkylate to avoid hydrogenating the alkyl benzene compounds, said hydrogenation being carried out by contacting said contacted detergent alkylate with a hydrogen containing gas in the presence of a catalyst at a temperature in the range of from about 50 F. to about 200 F. and at a pressure in the range of from about 5 p.s.i.g. to about 50 p.s.i.g.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to a method for the treatment of raw detergent alkylate in order to improve the color and odor characteristics of the alkyl benzene sulfonate produced from the alkylate by first contacting the raw detergent alkylate with activated charcoal to remove the major portion of the polynuclear aromatic compounds contained therein and thereafter hydrogenating the charcoal contacted alkylate under mild conditions to avoid hydrogenating the alkyl benzenes.

PRIOR ART The use of activated charcoal for the removal of im purities from organic solutions is, of course, Well known. No prior art is known, however, which shows the removal of polynuclear aromatic compounds from detergent alkylate i.e. alkylated benzene by contacting the alkylated benzenes with activated charcoal.

The hydrogenation of raw detergent alkylate is shown in US. Pat. No. 3,454,666 to Jacobs et al. In this patent the polynuclear aromatic compounds in raw detergent alkylate are selectively hydrogenated to produce saturated compounds and thereby improve the color and odor characteristics of the alkyl benzene sulfonates produced from the alkylate. It was found, however, that when the concentration of polynuclear aromatic compounds in the raw detergent alkylate was high that hydrogenation actually had a deleterious effect on the color and odor characteristics of the sulfonate detergent produced from the treated alkylate. It is believed that this results from a portion, at least, of the polynuclear aromatics being only partially hydrogenated, thus, creating a species of compounds which in the sulfonation step are more reactive and produce poorer color and odor characteristics in the sulfonate product than would be experienced if no hydrogenation had been attempted.

The present invention obviates the disadvantages of this process by first removing substantially all of the polynuclear aromatic compounds by contacting with charcoal and thereafter in the hydrogenation step the very small residual amounts of polynuclear aromatic compounds are completely hydrogenated along with the alkenyl benzenes produced in the alkylation step as well as certain other impurities of undetermined structure. This hydrogenation step is carried out under mild conditions as described in the aforementioned patent thereby avoiding hydrogenation of the alkyl benzenes.

The present invention also obviates the pollution efiFects and disadvantages of prior art detergent alkylate treating process wherein the alkylate was first acid treated, then caustic washed, and finally clay treated. The acid treatment is well known to be not completely satisfactory and in addition presents serious Waste disposal problems both of which disadvantages are obviated by the present invention.

SUMMARY OF THE INVENTION In accordance with the present invention raw detergent alkylate containing polynuclear aromatic hydrocarbons, alkenyl benzenes and other unsaturated compounds of undetermined structure all of which are produced during the alkylation reaction are percolated through or contacted with activated charcoal, in particular activated charcoal of bituminous origin, in order to remove substantially all of the polynuclear aromatic compounds, which compounds are generally present in amounts of the order of p.p.m. by weight but may be in higher concentrations but frequently are in lower concentrations.

The thus treated alkylate is then hydrogenated to saturate any small amounts of polynuclear compounds left in the alkylate and the alkenyl side chains of any alkenyl benzenes produced during the alkylation reaction as well as any other unsaturated compounds other than the desired alkylated benzenes. This method provides a finished detergent alkylate which when sulfonated in accordance with conventional sulfonation methods and neutralized to the desired salt gives a finished alkylated benzene sulfonate very low in Klett color and having excellent odor characteristics.

It is an object of this invention, therefore, to provide a method for treating detergent alkylate to improve the color and odor characteristics of the sulfonate produced from the treated alkylate.

It is another object of this invention to provide a method for treating detergent alkylate to replace the prior art acid treatment, caustic washing and clay filtration methods thereby avoiding the necessity of disposing of large quantities of used acid and clay with their attendant pollution problems.

It is another object of this invention to provide a method for treating raw detergent alkylate by first contacting the alkylate with activated charcoal and thereafter selectively catalytically hydrogenating the activated carbon treated-alkylate.

Other objects of this invention will be apparent from the following description of the preferred embodiments and from the claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The detergent alkylate to be treated in accordance with this invention is preferably that produced by the alkylation of benzene with monochlorinated paraffins, preferably straight chain having from 9 to 16 carbon atoms in the molecule and more preferably from 9 to 13 or from 10 to 14 carbon atoms using aluminum chloride as the alkylation catalyst. The alkylated benzene thus produced will have 9 to 16, 9 to 13 or 10 to 14 carbon atoms in the alkyl group, respectively. The method can be used, however, for branched chain alkyl benzenes as well and to alkyl benzenes produced by the aluminum chloride catalyzed alkylation of benzene with an olefin. The methods for producing detergent alkylate utilizing these reactants and catalyst are well known and the particular method used is not material to this invention. In all such methods, minor amounts, in general 100 p.p.m. or less, of polynuclear aromatics are produced. It has been found by ultraviolet spectroscopy that these polynuclear aromatics are anthracene, monoand di-short chain alkyl substituted anthracenes, naphthalenes (usually the short chain alkyl substituted naphthalenes) with only traces of phenanthrenes. No four or five ring compounds have been found. In addition to the polynuclear aromatic compounds, other undesirable impurities are produced during the alkylation reaction, for example, alkenyl benzenes and other unsaturated compounds of undetermined structure. If these compounds are allowed to remain in the detergent alkylate during sulfonation there is produced dark, highly colored compounds which render the detergent unsalable commercially for ordinary household use.

This raw alkylate can be percolated through a bed of activated charcoal at ambient temperatures and atmospheric pressure to remove selectively the polynuclear aromatic impurities from the detergent alkylate. The preferred activated charcoals are the commercial materials of bituminous origin, i.e. charcoal produced from lignite or bituminous coal. Other charcoals such as those made from petroleum, for example petroleum sludge, or charcoals made from wood or coconut shells and the like have been found to be inferior to the charcoals of bituminous origin in accomplishing the objects of this invention although they can be used.

The percolation rate of the raw alkylate through the charcoal bed can vary in accordance with the quantity of polynuclear aromatics in the alkylate and the particle size of charcoal. The percolation rate is not extremely critical, however, a rate of 1 ml. alkylate/gram charcoal/hr. to 50 ml. aLkylate/gram charcoal/hr. can be used with a rate of 3 mL/gram/hr. to 25 mlJgram/hr. being satisfactory in most instances. Either upflow or downflow through the charcoal can be used.

If the raw alkylate is too viscous for rapid percolation at room temperature, higher temperatures can be used at which the alkylate is more fluid, for example 150 F. or higher. Alternatively the raw alkylate can be diluted with a hydrocarbon which is less strongly adsorbed than the polynuclear aromatics, for example, liquid parafiin hydrocarbons such as hexane, octane and highly parafi'inic naphthas and the like. The used charcoal can be regenerated conventionally, but preferably simply burned.

The detergent alkylate obtained after being contacted with the charcoal treating step is subjected to hydrogenation under conditions of temperature, pressure, liquid hourly space velocity and hydrogen-containing gas such that the combined detergent alkylate feed and hydrogencontaining gas as it initially contacts the catalyst bed consists of a gas phase and a liquid phase wherein the liquid phase comprises substantially all of the alkylate charge to the reaction zone. The reaction is carried out under relatively mild conditions with particular attention to the temperature and pressure ranges in order to avoid hydrogenation of the alkyl benzenes and other undesired side reactions.

Although temperatures in the range of from about 50 F. to about 200 F. can be employed satisfactorily, it is preferred to maintain the temperature in the range of about 80 F. to 120 -F. At temperatures above about 200 F. the aforementioned undesired side reactions and hydrogenation of alkyl benzenes tend to occur, while at temperatures less than 200 F. the Klett colors and bromine numbers (indicating degree of unsaturation) of the sulfonated product tend to decrease and this decrease continues with decreasing temperature. At temperatures between about 120 F. down to 80 F. optimum decreases in the Klett colors and bromine numbers of the sulfonated alkyl benzene product are obtained. At temperatures below about 80 F. down to about 50 F. the conditions are generally so mild that except with the more active catalysts there may be incomplete hydrogenation, although as pointed out these temperatures can be used.

The hydrogenation can be carried out at pressures in the range of from 5 p.s.i.g. to about 50 p.s.i.g., but a somewhat more preferable range is from about 5 p.s.i.g.

to about 25 p.s.i.g. The hydrogenation can be carried out at any suitable liquid hourly space velocity depending upon the temperature and pressure employed since these are interrelated as is well known in the art, i.e., low space velocities for the lower temperatures and pressures and high velocities for the higher temperatures and pressures. A suitable range for the liquid hourly space velocity (volume of liquid feed mixture being hydrogenated per volume of catalyst per hour) is in the range of from about 0.5 to 3 although either higher or lower space velocities can be used as pointed out.

The hydrogen-containing gas utilized can be obtained from any suitable source such as from a reforming process or other similar refining process and it is not necessary that it be completely pure but it is preferred, however, that the gas contain at least 70 percent by volume of hydrogen in order to avoid unduly large reaction zone equipment. The hydrogen-containing gas can be partially or totally recycled and if necessary, conventional purification steps can be employed to remove contaminants from the gas before recycling to the reaction zone. Obviously the hydrogen-containing gas should not contain impurities which will react with the feed to the hydrogenation zone.

Suitable catalysts for the hydrogenation reaction include nickel on a support such as alumina (preferably from 5 to 15 weight percent or nickel expressed as elemental nickel), platinum or palladium on a support such as alumina or carbon (preferably 0.1 percent to 5 percent by weight of platinum or palladium expressed as the element), cobalt and molybdenum oxides on a support such as alumina (preferably 1 percent to 5 percent by weight of cobalt oxide expressed as C00 and 5 percent to 25 percent by weight of molybdenum oxide expressed as M00 or tungsten and nickel oxides or sulfides (preferably containing tungsten and nickel in a ratio of 3:1 to 10:1 by Weight).

A particularly preferred catalyst for the hydrogenation reaction of this invention is one which consists essentially of palladium supported on a suitable base such as, for example, carbon or the inorganic oxides such as alumina, silica, boria, magnesia, zirconia, and the like or mixtures of these oxides. A particularly suitable catalyst for the hydrogenation step is one having from about 0.1 percent to about 1 percent of palladium deposited on alumina or carbon. The catalyst can be in the form of spheres, pellets, or powder depending upon the particular process used, with spheres being preferred.

The hydrogenation reaction may be used in either a batch or continuous type operation utilizing either a fluidized bed reaction zone, or a fixed bed reaction zone. It is preferred that the reaction be carried out utilizing a fixed bed with upflow through the reaction zone although downflow operation has also been found to be suitable. The fixed bed is preferred since it requires the least capital expenditure and can be operated With the lowest catalyst loss. In the upflow system the liquid detergent alkylate feed and the hydrogen are fed co-currently upwardly through the bed.

The alkylate after being hydrogenated can be used directly in the sulfonation reaction utilizing any of the ordinary sulfonation methods including sulfonation with sulfur trioxide, concentrated sulfuric acid, oleums, chlorosulfonic acid, and the like. The resulting alkyl benzene sulfonic acids can be neutralized in accordance with well known methods to produce the desired salt, usually, the sodium salt. If a solvent has been used to dilute the raw alkylate prior to contacting with carbon, the solvent can be stripped from the alkylate prior to the hydrogenation step or it can be allowed to remain and pass through the hydrogenation step where it undergoes no reac= tion since it is already saturated and thereafter the solvent can be stripped from the alkylate prior to sulfonation if it is so desired.

The following examples are provided to further illustrate the invention.

EXAMPLE I A commercial raw detergent alkylate having from to 13 carbon atoms in the alkyl group with the average being about 11.4 with a bromine index of III and containing approximately 30 ppm. by weight of polynuclear aromatics, primarily anthracene and substituted anthracenes was utilized as the charge material for the runs of this example. The activated charcoal employed was a commercial material prepared from bituminous coal and which had pores which were essentially cylindrical. This material is well known, commercially available and utilized for charcoal percolation processes. The activated charcoal treatment method employed consisted of passing the detergent alkylate to be treated through a bed of 100 ml. (approximately 44 grams) of the activated charcoal contained in a tube approximately 4.5 feet in length at a rate of 1 liter per hour. In each percolation run 5 liters of the alkylate were passed over the charcoal in this manner and it was found that the charcoal had not reached saturation with respect to removal of the polynuclear aromatics. In all of the runs as set forth herein the charcoal percolation was upfiow through the bed, although in other runs no difference in upflow and downflow treatment was observed. In run No. 1 the raw detergent alkylate was first hydrogenated and thereafter charcoal treated and in run No. 2 the raw alkylate was first charcoal percolated and then hydrogenated. In each hydrogenation treatment the catalyst consisted of one percent palladium deposited on alumina beads (l820 mesh size) a commercial catalyst. The conditions were 80 E, 10 p.s.i.g., a liquid hourly space velocity of 6-8 and 2000 standard cubic feet of hydrogen per barrel of feed. In both runs the resulting bromine index was 6 and the Klett color after S0 sulfonation and neutralization to the sodium salt was 49 in run No. 1 and 26 in run No. 2. These results demonstrate that the process of this invention substantially reduces the bromine index and that in order to develop low Klett colors on the sulfonated product it is necessary to treat with activated carbon before hydrogenating. It is generally believed that if the hydrogenation is carried out prior to activated carbon treatment some of the polynuclear aromatics are only partially hydrogenated and that these partially hydrogenated products are more highly colored and less readily absorbed by the activated carbon. Numerous similar runs have shown the necessity for treating the alkylate with activated carbon prior to the hydrogenation step rather that reversing these steps.

EXAMPLE II A number of charcoal runs were carried out under essentially the same conditions as in Example I utilizing various commercially available activated charcoals from various sources including those having a coconut shell origin, petroleum sludge origin, lignite origin, and bituminous coal origin (but wherein the pores were of a more conical shape than the cylindrical shape of the bituminous coal charcoal of Example I). These were all found to be operable in reducing the polynuclear aromatic hydrocarbon content of the detergent alkylate, however, they are not as good as the charcoal of Example I. In addition, other commercial detergent alkylates having different polynuclear aromatic contents were charcoal treated as in Example I and substantially all of the polynuclear aromatics were removed. These various alkylates which had been charcoal treated were also subjected to the hydrogenation step and it was found that improved Klett colors and low bromine numbers were obtained for the sulfonates produced from them. In addition, the odor characteristics were greatly improved and the sulfonates met commercially acceptable specifications. Additional hydrogeuation runs were carried out on the activated carbon treated alkylates at temperatures as high as 250 F., for example, and at high pressures, for example, up to 400 p.s.i.g. and in all such cases poorer Klett colors and higher bromine numbers were obtained than when the 6 hydrogenation was carried out within the ranges specified for this invention.

It was found that when the raw alkylate was treated in accordance with this invention the bromine number and color of the treated alkylate was also markedly improved so that the finished alkylate met commercial specifications. Since, however, the detergent alkylate is only the intermediate the alkylates were all sulfonated by the method for purposes of comparison and the colors, bromine numbers and odors of the finished sulfonate were also found to meet commercial acceptability.

The results of all of these experiments demonstrate that in order to attain the objects of this invention it is necessary to first contact the raw detergent alkylate with activated carbon and thereafter hydrogenate the carbon treated alkylate under the mild conditions specified. It should be pointed out that the amount of hydrogen employed is not critical but is preferred to be in a sufliciently large excess over the rather small stoichiometric amounts to provide the desired hydrogenation conditions which have been described and the unreacted hydrogen can be recycled with make-up as described.

I claim:

1. A method for improving the color and odor characteristics of a detergent alkylate material containing alkylated benzenes having from 9 to 16 carbon atoms in the alkyl group, polynuclear aromatic compounds and alkenyl benzenes which comprises contacting said detergent alkylate with activated charcoal and thereafter contacting the charcoal treated alkylate in a reaction zone with a hydrogen-containing gas in the presence of a hydrogenation catalyst at a temperature in the range of from about 50 F. to 200 F. and at a pressure in the range of from about 5 p.s.i.g. to about 50 p.s.i.g.

2. The method according to claim 1 wherein the alkyl group of the alkylated benzenes contain from 9 to 13 carbon atoms.

3. The method according to claim 1 wherein the alkyl group of the alkylated benzenes contain from 10 to 14 carbon atoms.

4. The method according to claim 1 wherein the activated charcoal is of bituminous origin.

5. The method according to claim 1 wherein the detergent alkylate is contacted with said charcoal at a rate ranging between 1 ml. alkylate/gram charcoal/hour to 50 ml. alkylate/ gram charcoal/hour.

6. The method according to claim 1 wherein the catalyst is palladium on a carbon or alumina support.

7. The method according to claim 6 wherein the catalyst comprises 0.1 to 1 percent by weight palladium on alumina.

8. The method according to claim 1 wherein the hydrogenation step is carried out at a temperature in the range from about 80 F. to F. and a pressure in the range of from about 5 p.s.i.g. to 25 p.s.i.g.

9. The method according to claim 8 :wherein the liquid hourly space velocity is in the range of from about 0.5 to 3.0 volumes of liquid feed per volume of catalyst per hour.

10. A method according to claim 8 wherein the alkylate is passed upwardly through the hydrogenation reaction zone.

References Cited UNITED STATES PATENTS 2,395,491 2/1946 Mavity 260-674 2,703,330 3/1955 Bloch et al. 260674 2,717,864 9/1955 Charlet et al 260674 2,932,677 4/1960 Kirk et al. 260-674 3,454,666 7/1969 Jacobs et al. 260-674 DELBERT E. GANTZ, Primary Examiner C. E. SPRESSER, 111., Assistant Examiner US. Cl. X.R. 260 505 P, 671 B 

